#include  <cstdio>

struct point
{
	double x,y;
};

int main(int argc, char *argv[])
{
	int n;
	struct point pre,now,first;
	while( scanf("%d",&n) != EOF )
	{
		scanf("%lf%lf",&pre.x,&pre.y);
		first = pre;
		printf("%d",n);
		for( int i = 1; i < n ; ++i )
		{
			scanf("%lf%lf",&now.x,&now.y);
			double x,y;
			x = (pre.x+now.x)/2;
			y = (pre.y+now.y)/2;
			printf(" %lf %lf",x,y);
			pre = now;
		}
		double x,y;
		x = (pre.x+first.x)/2;
		y = (pre.y+first.y)/2;
		printf(" %lf %lf\n",x,y);
	}
}
